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The turbine consists of a cylindrical water wheel or runner with a horizontal shaft, composed of numerous blades (up to 37), arranged radially and tangentially. The blade's edges are sharpened to reduce resistance to the flow of water. A blade is made in a part-circular cross-section (pipe cut over
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Another advantage is that it can often clean itself. As the water leaves the runner, leaves, grass etc. will not remain in the runner, preventing losses. Therefore, although the turbine's efficiency is somewhat lower, it is more reliable than other types. No runner cleaning is normally necessary,
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needed, and the available water. The ratio is that (0–100%) of the water is admitted to 0-100%×30/4 blades. Water admission to the two nozzles is throttled by two shaped guide vanes. These divide and direct the flow so that the water enters the runner smoothly for any width of opening. The guide
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Cross-flow turbines are often constructed as two turbines of different capacity that share the same shaft. The turbine wheels are the same diameter, but different lengths to handle different volumes at the same pressure. The subdivided wheels are usually built with volumes in ratios of 1∶2. The
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for his turbine design in 1903, and the manufacturing company
Weymouth made it for many years. Ossberger's first patent was granted in 1933 ("Free Jet Turbine" 1922, Imperial Patent No. 361593 and the "Cross Flow Turbine" 1933, Imperial Patent No. 615445), and he manufactured this turbine as a
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The water flows through the blade channels in two directions: outside to inside, and inside to outside. Most turbines are run with two jets, arranged so two water jets in the runner will not affect each other. It is, however, essential that the turbine, head and turbine speed are harmonised.
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subdivided regulating unit, the guide vane system in the turbine's upstream section, provides flexible operation, with 33, 66 or 100 % output, depending on the flow. Low operating costs are obtained with the turbine's relatively simple construction.
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is produced during the periods when rivers have low flows. If the turbines used have high peak efficiencies, but behave poorly at partial load, less annual performance is obtained than with turbines that have a flat efficiency curve.
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turbine. However, the cross-flow turbine has a flat efficiency curve under varying load. With a split runner and turbine chamber, the turbine maintains its efficiency while the flow and load vary from 1/6 to the maximum.
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The water flows first from the outside of the turbine to its inside. The regulating unit, shaped like a vane or tongue, varies the cross-section of the flow. The water jet is directed towards the cylindrical runner by
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The turbine geometry (nozzle-runner-shaft) assures that the water jet is effective. The water acts on the runner twice, but most of the power is transferred on the first pass, when the water enters the runner. Only
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Due to its excellent behaviour with partial loads, the cross-flow turbine is well-suited to unattended electricity production. Its simple construction makes it easier to maintain than other turbine types; only two
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220:, the water is admitted at the turbine's edge. After passing to the inside of the runner, it leaves on the opposite side, going outward. Passing through the runner twice provides additional
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vanes should seal to the edges of the turbine casing so that when the water is low, they can shut off the water supply. The guide vanes therefore act as the valves between the
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e.g. by flow inversion or variations of the speed. Other turbine types are clogged more easily, and consequently face power losses despite higher nominal efficiencies.
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to disks to form a cage like a hamster cage and are sometimes called "squirrel cage turbines"; instead of the bars, the turbine has the trough-shaped steel blades.
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Although the illustration shows one nozzle for simplicity, most practical cross-flow turbines have two, arranged so that the water flows do not interfere.
216:, which have axial or radial flows, in a cross-flow turbine the water passes through the turbine transversely, or across the turbine blades. As with a
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must be maintained, and there are only three rotating elements. The mechanical system is simple, so repairs can be performed by local mechanics.
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standard product. Today, the company founded by
Ossberger which bears his name is the leading manufacturer of this type of turbine.
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and turbine. Both guide vanes can be set by control levers, to which an automatic or manual control may be connected.
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Since it has a low price, and good regulation, cross-flow turbines are mostly used in mini and
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The cross-flow turbine is of the impulse type, so the pressure remains constant at the runner.
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are sometimes called cross-flow turbines since the flow passes through the rotor transversely
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of the power is transferred to the runner when the water is leaving the turbine.
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The peak efficiency of a cross-flow turbine is somewhat less than a
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The regulating device controls the flow based on the
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337:and with heads less than 200 m (660 ft).
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472:List of conventional hydroelectric power stations
204:and the German Fritz Ossberger. Michell obtained
248:its whole length). The ends of the blades are
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410:Popular Science, May 1977, Vol. 210, No. 5
120:Learn how and when to remove this message
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58:adding citations to reliable sources
264:to the active cylindrical blades.
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497:Run-of-the-river hydroelectricity
151:— turbine casing (all thick grey)
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333:units of less than one thousand
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477:Pumped-storage hydroelectricity
136:Diagram of a Cross-flow turbine
45:needs additional citations for
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196:developed by the Australian
408:Water power for your home,
380:Vertical axis wind turbines
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243:Ossberger turbine section
340:Particularly with small
271:Ossberger turbine runner
342:run-of-the-river plants
161:— removable rear casing
540:Gorlov helical turbine
386:Gorlov helical turbine
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186:Bánki-Michell turbine
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69:"Cross-flow turbine"
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141:— air-venting valve
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182:cross-flow turbine
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235:Details of design
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27:Water turbine
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18:Banki turbine
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545:Pelton wheel
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52:Please help
47:verification
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560:Water wheel
487:Micro hydro
482:Small hydro
350:electricity
218:water wheel
202:Donát Bánki
492:Pico hydro
460:generation
450:Hydropower
393:References
309:Advantages
222:efficiency
80:newspapers
518:equipment
575:Category
412:, 87-93.
369:See also
359:bearings
282:penstock
176:— shaft
166:— blades
156:— runner
319:Francis
293:⁄
206:patents
94:scholar
346:rivers
323:Pelton
315:Kaplan
258:nozzle
250:welded
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